Edexcel A Level Statistics

Which dates does the Large Data Set cover?

May-October 1987

May-October 2015

What are the 5 UK weather stations?

Camborne (Cornwall)

Heathrow (near London)

Hurn (Dorset - south coast)

Leeming (Yorkshire - North England)

Leuchars (Scotland)

What are the 3 overseas weather stations?

Beijing (China)

Jacksonville (Florida, USA)

Perth (Australia)

What does tr mean?

trace - less than 0.05mm of rainfall

Histogram - frequency density equations

area of bar = k x frequency

frequency density = frequency / class width

Comparing data

Comment on:
- a measure of location
- a measure of spread

Conditions for Binomial distribution

- there are a fixed number of trials, n
- there are two possible outcomes (success and failure)
- there is a fixed probability of success, p
- the trials are independent of each other

Summary Statistic / Sₓₓ

Sₓₓ = Σ(x - x̄)²
Sₓₓ = Σx² - (Σx)² / n

Stratified sampling - Adv & Disadv

Adv
- Sample accurately reflects the population structure
- Guarantees proportional representation of groups within a population

Disadv
- Population must be clearly classified into distinct strata
- Selection within each stratum suffers from the same disadvantages as simple random sampling

Systematic sampling - Adv & Disadv

Adv
- Simple and quick to use
- Suitable for large samples and large populations

Disadv
- A sampling frame is needed
- It can introduce bias if the sampling frame is not random

Simple random sampling - Adv & Disadv

Adv
- Free of bias
- Easy & cheap to implement for small populations and small samples
- Each sampling unit has a known and equal chance of selection

Disadv
- Not suitable when the population size or the sample size is large
- A sampling frame is needed

Census - Adv & Disadv

Adv
- Completely accurate

Disadv
- Time consuming & expensive
- Cannot be used when the testing process destroys the item
- Hard to process large quantity of data

Census

Observes or measures every member of a population

State four properties of the normal distribution.

Symmetrical, bell-shaped, mean = median = mode, total area under curve = 1.

What is the standard normal distribution?

Z∼N(0,1) with mean 0 and standard deviation 1.

How do you standardise a normal variable?

When can a binomial distribution be approximated by a normal distribution?

• n is large

• p is close to 0.5

State the formula for conditional probability.

What must you do when normal-approximating?

The mean and variance of a binomial distribution can be calculated by:

µ =np

σ = np(1-p)

Apply conituity correction (as binomial distribution is discrete and the normal distribution is continuous)

when does μ stay the same but σ gets divided by √n

Sample of another sample (typically normal)

what does Φ(a) mean

P ( Z score < a)

What is cloud coverage is measured in?

Measured in oktas which can be measured in integer values 0-8.